Over the last several decades, more and more surgeons are abandoning traditional open methods of gaining access to vital organs and body cavities in favor of endoscopes and endoscopic instruments which access organs through small puncture-like incisions. Endoscopic instruments are inserted into the patient through a cannula, or port, that has been made with a trocar. Typical sizes for cannulas range from three millimeters to twelve millimeters. Smaller cannulas are usually preferred, and this presents a design challenge to instrument manufacturers who must find ways to make surgical instruments that fit through the cannulas and operate in a safe and effective manner.
Endoscopic instruments for arresting blood loss and coagulating tissue are well known in the art. For example, several prior art instruments employ thermal coagulation (heated probes) to arrest bleeding. However, due to space limitations surgeons can have difficulty manipulating the instruments to coagulate, desiccate, fulgurate and/or cut tissue. Moreover, if the probe comes into close contact with the tissue, the probe may adhere to the eschar during probe removal possibly causing repeat bleeding. Other instruments direct high frequency electric current through the tissue to stop the bleeding. Again, eschar adherence may also be a problem with these instruments. In both types of instruments, the depth of the coagulation is difficult to control.
U.S. Pat. No. 5,207,675 to Canady attempts to resolve certain of the above-noted problems with respect to the prior art by providing a tube-like coagulation instrument in which an ionizable gas is forced through the instrument and ionized by an electrode in the region between the distal end of the instrument and the bleeding tissue. The electrode, then, does not contact the tissue.
U.S. Pat. No. 5,720,745 to Farin et al. discloses a coagulation instrument which extends through a working channel of an endoscope and includes an electrode for ionizing a stream of ionizable gas exiting the distal end of the instrument at a rate of less than about 1 liter/minute. As explained in detail in the Farin et al. specification, the purpose of discharging the gas at a very low flow rate is to effectively cloud the tissue area and create an ionizable gas xe2x80x9catmospherexe2x80x9d to gently coagulate the tissue.
Using these instruments to treat certain more tubular sites, e.g., the esophagus and/or colon, is often difficult, impractical and time consuming. For example, these longitudinally oriented instruments fire the ionized gas and the RF energy in an axial direction from their respective distal ends which, in the case of tubular tissue, would be parallel to the bleeding tissue. Thus, manipulating these instruments to focus the energy transversely or off-axis at the bleeding tissue may be very difficult.
Thus, a need exists for the development of a new and effective instrument for treating certain more tubular tissue.
The present disclosure relates to an electrosurgical apparatus for coagulating tissue which includes an elongated flexible tube having a proximal end, a distal end a source for supplying pressurized ionizable gas to the proximal end of the tube. The apparatus in one embodiment includes a hollow sleeve made from a shape memory alloy, e.g., Nitinol and/or Tinel, which has a generally curved austenite state and displays stress-induced martensite behavior at normal body temperatures. The hollow sleeve is restrained in a deformed stress-induced martensite configuration within the tube wherein partial extension of a portion of the hollow sleeve from the tube transforms the portion from the deformed configuration to its generally curved austenite configuration such that the portion directs the gas transversely at the tissue. The surgical apparatus also includes at least one active electrode and a source of high frequency electrical energy for ionizing the gas prior to the gas exiting the portion of the sleeve.
Preferably, the angle at which the gas is directed at the tissue is directly related to the distance the portion of the sleeve extends from the tube.
In another embodiment of the present disclosure, the electrosurgical apparatus includes a wire connected to the distal end of the tube. The wire is movable from a first generally relaxed position wherein the tube is disposed in generally rectilinear parallel fashion relative to the tissue to a second retracted position wherein the distal end of the tube flexes at an angle to direct the gas towards the tissue. Preferably, the angle at which the gas is directed at the tissue is directly related to the amount of tension placed on the wire.
Another embodiment includes a corona electrode disposed proximate the distal end of the tube for inducing ignition of the plasma prior to emission. A wire is used to articulate the distal end of the tube and direct the gas at the tissue. Preferably, the wire is connected to the corona electrode and electrically connects the corona electrode to a source of electrosurgical energy. A dielectric material is preferably disposed between the corona electrode and the active electrode to prevent arcing between electrodes.